FI120582B - Utfällningskiseldioxid - Google Patents

Abstract

Novel silicas in the form of powder and spherical beads or granules. The silicas are characterized by having a specific CTAB surface of 100-140 m2/g, a small median diameter, following disaggregation by ultrasound means, and optionally, a porous distribution so that the porous volume occupied by the pores whose diameter is 175-275 ANGSTROM is less than 55% of the porous volume occupied by the pores having diameters of 400 ANGSTROM or less. The invention also concerns a method for the preparation of said silicas and their use as reinforcing fillers for elastomers.

Description

FIELD OF THE INVENTION The present invention relates to novel novel silica, in particular in the form of powder, substantially round spheres or granules, for the process for their preparation and their use as reinforcing fillers for elastomers.

It is known that silica has long been used as a special reinforcing filler for elastomers, especially in pneumatic tires.

As with all reinforcing fillers, it must be easy to handle on the one hand, and easy to incorporate on the other hand, especially in mixtures.

15

It is known that, in general, optimum reinforcement properties of fillers can be achieved when the filler is in an elastomeric matrix in a final form which is both finely divided and as homogeneously distributed as possible. However, such goals will only be achieved if, on the other hand, the filler mixes: very easily into the matrix during the mixing of the elastomer • (filler incorporation) and decomposes, deagglomerates, · · ·. . ·. on the other hand, the · · ·. * / powder formed during the deagglomeration step is completely and homogeneously dispersed in the · · · elastomer (powder dispersibility).

• · · • · ·

In addition, due to their mutual affinity, the silica particles have an embarrassing tendency to agglomerate in the elastomer matrix. Because of this silica / silica interaction, the reinforcing effect remains substantially weaker than that theoretically possible. if all the silica / elastomer interactions that may be created during the mixing step are actually achieved (this theoretical amount of silica / elastomer interaction is known to be directly related to the external surface of the silica used).

2

In addition, such silica / silica interactions 5 easily increase the stiffness and consistency of the blends in the raw state and thus make their use more difficult.

The problem is to provide fillers which are not only relatively large in particle size but also very dispersible in the elastomers.

It is an object of the present invention to overcome the above-mentioned drawbacks and to solve the said problem.

Specifically, the object is novel novel precipitated silica, usually in the form of powder, substantially round spheres or granular masses, while being relatively large in size, dispersible (non-agglomerated) and generally more reinforcing in a very satisfactory manner.

The invention also relates to a process for the preparation of these precipitated oxides.

The invention further relates to the use of these precipitated silica as reinforcing fillers in the elastomers to which they impart. · ···. excellent mechanical properties.

The main object of the invention is to provide highly dispersible (and deagglomerating) sludge silica, which have very good reinforcing properties, and preferably the following: *: * · The silica is also relatively great.

• ·

«M

• t • · M · ·. In the following, the term "BET specific surface area" 35 refers to the specific surface area determined by the Brau-Emmett-Teller method described in " The Journal of the American Chemical Society, Vol. 60: 309, Feb. 1938, and the corresponding standard NFT 45007 (November 1987).

5 The CTAB surface is the outer surface as determined by NFT 45007 (November 1987) (5.12).

The oil absorption value DOP was determined according to NFT 30-022 using 10 (March 1953) dioctyl phthalate.

The filling density in the compressed state (DRT) is measured according to NFT-030100.

Finally, it is stated that the given pore volumes are measured with a mercury pore meter, the pore diameters are calculated at a Washburn ratio at a contact angle of 130 ° and a surface tension gamma of 484 dynes / cm (pore meter MICROMERITICS 9300).

20

The dispersing and deagglomerating capacity of the silicas of the invention can be quantified by a special deaggloid · *** · fermentation test.

• · m • · · · · ·; Such a deagglomeration test was performed as follows: The cohesion of the agglomerates was evaluated by a granulometric measurement (diffraction laser) performed on a silica suspension of pre-deagglomerated by ultrasonic treatment; • · · ·. · * 30 thus measured the deagglomeration capacity of silica (0.1 · · ·: ... · micron to decomposition of objects up to a few tens of microns). VIBRACELL BIOBLOCK (600 W) with a sensor diameter of 19 · · *! 'mm Granulometer measurement was performed with a diffraction laser at 35 granulometers SYMPATEC.

• • • • • • • • 4

2 grams of silica were weighed in a granulator (height 6 cm, diameter 4 cm) and supplemented with 50 grams of water permuted to give a 4% silica water suspension which was homogenized for 2 minutes by magnetic stirring. The ultrasonic agglomeration was then carried out in the following manner: with the sensor at a depth of 4 cm, the input intensity was adjusted to obtain a 20% power scale pointer deviation (equivalent to 120 watts / cm2 energy loss of the sensor cover). Deagglo-10 mererization was continued for 420 seconds. Granulometric measurement was carried out when a known amount of homogenized suspension (expressed in ml) was introduced into the volume granulometer container.

The resulting average diameter value of 0 50 is less the more significant the ability of the silica to deagglomerate. The ratio (10 x volume of suspension injected (in ml) / optical density of the suspension observed on the granulometer (this optical density is in the order of 20) was also determined. This ratio indicates the number of fine particles, i.e. less than 0.1 µm This ratio, called ultrasound agglomeration factor (FD), is the greater the more significant the ability of silica to deagglomerate.

• · · • · · • •. . ·. The ultrasonic agglomeration factor (FD) of the silica according to the first embodiment of the invention is greater than 3 ml, preferably more than 4 · 4 ml, for example more than 4.5 ml.

An embodiment of the invention is a novel type of precipitated silica, characterized by its The specific surface area of the CTAB (SCTAB) is 100-140 m2 / g, preferably 100-135 m2 / g, the pore distribution is such that a pore volume of 35 consisting of pores having a diameter of 17.5 to 27.5 nm represents less than 50% of the pore volume formed by pores having a diameter of 40 nm or less, an average diameter after ultrasonic agglomeration of 5 (05O) less than 4.5 µm, preferably less than 4 µπι, for example less than 3.8 µππ.

Thus, one of the features of the silica according to an embodiment of the present invention also relates to a pore volume distribution, in particular a pore volume distribution formed by pores having a diameter of 10 nm or less. This latter volume corresponds to the useful pore volume of the fillers used to reinforce the elastomers. The porogram analysis shows that the silicas of the second embodiment of the invention are such that less than 50%, in particular less than 40%, in some special cases less than 30% of the pore volume gain is comprised of pores having a diameter in the range 17.5-27.5 nm.

Generally speaking, the silicon dioxide of the second embodiment of the present invention has an ultrasonic agglomeration factor (FD) of greater than 3.0 mL, for example, greater than 3.9 mL.

• # · #

The silica of the invention has a BET specific surface area (SBET)

• M

. 100-210 m2 / g, especially 100-180 m2 / g.

• · 1. ·. : 25 • · ·

According to one embodiment of the invention, the ratio of silicon dioxide to SBEJ / (S ^ J is 1.0 to 1.2, i.e., the micro porosity of these silicas is low.

According to another embodiment of the invention, the ratio of silica ··· · ... · (SBET) / (SCTAB) is greater than 1.2, for example 1.21 to 1.4, i.e., ♦ · 1 · '♦ The micro-porosity of the silica is relatively high.

• ♦ ♦ · •

The silicon dioxide according to the invention has an oil absorption value DOP generally of 150-400 ml / 100 g, in particular 180-350 ml / 100 g, for example 200-310 ml / 100 g.

The silicas of the invention may be in the form of powder, substantially round spheres or possibly granules, and are characterized in that, although relatively large in size, they exhibit good deagglomeration and dispersion properties and exhibit very satisfactory reinforcing properties. Their deagglomeration and dispersion properties are thus preferably better, the specific surface is the same or rather the same, and the particle size is the same or almost the same as that of the prior art silica.

15

The silica powder of the invention should have an average size of at least 15 µπι; and can be, for example, 20-150 µm, for example 30 0-100 µπι.

These powders typically have a bulk density (DRT) of at least 0.17, for example 0.2 to 0.3.

• · · «· · • · ·. ** ·. The total pore volume of these powders is usually small. at least 2.5 cm 3 / g, in particular 3-5 cm 3 / g.

• · · • · ·. . 25 • · · · ·. *. * They reach a very satisfactory trade-off in terms of • · · · * / final / mechanical properties in the vulcanized • · · · · *.

• · · V: 30 They also provide excellent precursors for synthesizing the granules described below.

• · • · · · ·

The substantially round spheres according to the invention should preferably have an average size of at least 80 µπι.

: 35 • · • * · • · · · · 7

In some embodiments of the invention, the average sphere size is at least 100 µιη, for example, at least 150 µm. Usually it is up to 300 μιη and is preferably in the range 100-270 μπι. This average size is determined by 5 NF X 11507 (November 1970) by dry screening and determination of the corresponding diameter with 50% cumulative reject.

These granules have a bulk density (DRT) of at least 0.17, for example 0.2 to 0.32.

They generally have a total pore volume of at least 2.5 cm 3, in particular 3-5 cm 3 / g.

As already discussed above, such silica, which consists of substantially spherical spheres, preferably full, homogeneous, low dust, and highly cellular granules, is highly deagglomerated and highly dispersible. In addition, it has excellent gain. Such silica 20 further provides excellent precursors for synthesizing the powders and granules of the invention.

• ♦ · • · ·. ***. Preferably, these spheres are * · · of another embodiment of the invention. . ·. comply with; preferably, they have an average diameter (0 50) of less than 3.1 μιη after ultrasonic agglomeration and an ultrasonic • agglomeration factor (FJ of more than 8 ml, for example greater than 12 ml).

• · · · · · · · · · · · · · ·

The grain masses according to the invention preferably have a grain size of at least 1 mm, in particular from 1 to 10 mm, in the direction of their largest dimension (length) • · · *. * * 30.

The granules of these granules can have very different shapes. For example, spherical, • · *! ' cylindrical, parallelepipeds, tablets, strips, pellets ·, · 35 and cross-sectional or multi-sectional extrudates.

These granules usually have a bulk density in the compressed state (DRT) of at least 0.27 and may be at most 0.37.

They generally have a total pore volume of at least 1 cm 3 / g, in particular 1.5 to 2 cm 3 / g.

It is preferable to prepare the silicas of the invention by a process type which reacts with an alkali metal M 10 silicate acidifying agent to obtain a suspension of precipitated silica and then separating and drying. The process is characterized in that the precipitation is carried out in the following manner: i) forming a base of a vessel containing a portion of the total amount of silicate of the alkali metal M used for the reaction, expressed as SiO 2 in this base, up to 11 g / l; until at least 50% of the amount of M20 present in this base is neutralized, .1 · 1. iii) is added to the reaction mixture simultaneously and an acidifying agent. . ·. the amount of silicate added (expressed as · · · .1 as SiO)) / amount of silicate present in the base (expressed as · · · ··· 1 SiO)) 12-100.

• · · λ ’• · · · · ·

Thus, it has been found that a very low silicate content as SiO 2 · · · · · · · · · · · · · · · · · · · · · ·% (expressed as the base) and a suitable consolidation value at the same · · · addition step are important conditions for the obtained products to have excellent properties.

••••••••••••••••••••••••••••••••••••••••••••••••••••• ·

It should be noted that, in general, this particular process is a process for synthesizing the precipitated silica, i.e. therein, the acidifying agent is reacted with an alkali metal M silicate.

5 The acidifying agent and the silicate are selected in a manner known per se. It should be noted that the substances which are commonly used as acidifying agents are strong inorganic acids such as sulfuric acid, nitric acid and hydrochloric acid, and organic acids such as acetic acid, formic acid and carbonic acid.

10

As the silicate, any conventional silicate form can be used, for example, metasilicates, disilicates, and preferably alkali metal M silicates, where M is sodium or potassium.

15

The acidifying agent is usually sulfuric acid and the silicate is sodium silicate.

When sodium silicate is used, the molar ratio SiO 2 / Na 2 O is 2 to 4, especially 3.0 to 3.7.

: Again, especially with regard to the manufacturing process according to the invention. the precipitation into the process is specifically carried out in the following steps.

First, a base portion of the vessel containing the silicate is formed.

• * ·. *. * The amount of silicate present in this basic amount should preferably be only a fraction of the total amount of silicate used in the reaction.

♦ ♦♦ V · 30 An essential feature of the manufacturing process of this invention is that the silicate content of the base of the vessel is. up to 11 g SiO2 / liter. This concentration may be up to 8 g / l.

••••••••••••••••••••••••••

The conditions for the silicate contents in the base of the vessel partially regulate the characteristics of the resulting silicates.

The base of the vessel may contain an electrolyte. However, it is more preferred that no electrolyte is used in the process of this invention; in particular, it is preferred that no electrolyte is used in the base of the vessel.

The term electrolyte as used herein has the usual meaning, i.e., it denotes any ionic or molecular substance which decomposes or dissociates in solution to form ions, i.e. charged particles. Among the electrolytes, mention may be made of the salts of the alkali metal and alkaline earth metal salts, in particular the starting silicate metal salt and the acidifying agent, for example sodium sulfate, in the case of reaction of sodium silicate with sulfuric acid.

In a second step, an acidifying agent is added to the base composition as previously described.

20

Thus, in a second step, the acidifying agent is added to the base of the vessel: 1 2: until at least 50% of the M · 0 present in this base of the vessel is neutralized.

Preferably, in this second step, an acidifying agent is added to the base portion of the vessel until 50-99% of the amount of M20 present in the base is neutralized.

• · · • · ·

The acidifying agent can be diluted or concentrated and has a ··· * .1 1 30 normality of 0.4 to 36 N, for example 0.6 to 1.5 N.

• · · • · • · ···

In particular, in the case where the acidifying agent is sulfuric acid, »· ·, ·· ♦. the preferred concentration is 40-180 g / l, for example 60-130 g / l.

• · ··· • · · · · ♦ ♦♦ ♦ ♦ ♦ · 2 • · · 3 • · 11

Thus, when the desired value of neutralized M20 is reached, the acidifying agent and the alkali metal M silicate are added simultaneously so that the value of consolidation, i.e. the amount of silicate added / amount of silicate present in the basic portion of vessel 5, is 50, especially 13-40.

Preferably, the amount of acidifying agent to be added throughout step iii) should be such that 80-99%, for example 10 85-97%, of the added M20 is neutralized.

In step iii), it is possible to carry out the simultaneous addition of the acidifying agent and the silicate at the first pH of the reaction mixture, then at the second pH2 of the reaction mixture, so that 7 <pH2 <pH2 <9.

The acidifying agent used in step iii) may be diluted or concentrated and may have a normality of 0.4 to 36 N, for example 0.6 to 1.5 N.

20

In particular, when this acidifying agent is sulfuric acid, it should be present in a concentration of 40-180 g / l, for example 60-130 g / l.

·· · · · · · · ···

. ·, M of the alkali metal usually added during step iii)

• · · • · ·, ·,; The content of 25 silicates, expressed as silica, is 40 to 330 g / l, for example 60 to 250 g / l.

The actual precipitation reaction is complete when all the remaining amount of silicate is added.

• · · V: 30 ··· ί.,. Σ It may be advantageous, especially after the simultaneous addition mentioned above, to ripen the reaction mixture, this • · · tI ··, ignition may take for example 1-60 minutes, especially '! 1 5-30 minutes.

• · · - r- • · · 3 5 · • · ·

• M

• t 12

Furthermore, it is advisable to add an additional amount of acidifying agent to the reaction mixture after precipitation as a final step, especially after any maturation. Usually the addition is continued until the pH of the reaction mixture reaches 3 to 5.5, preferably 4 to 5.5. In particular, it is capable of neutralizing the total amount of M20 added in step iii) and adjusting the pH of the final silica to the value desired for a particular application.

The acidifying agent used in this addition step is usually the same as that used in step iii) of the process of the invention.

The temperature of the reaction mixture is usually 60-98 ° C.

15

Preferably, the acidifying agent of step ii) is added to the base portion of the vessel having a temperature of 60-96 ° C.

In one embodiment of the invention, the reaction is carried out at a vacuum of 75 to 96 ° C. In another embodiment of the invention, the reaction end-side temperature is higher than; the first half of the reaction temperature. At the beginning of the reaction, the temperature can be ·· «. ·· *. preferably maintained at 70-96 ° C, then the temperature is increased · · ·. . ·. during the reaction for a few minutes, preferably to 80 · 98 ° C, and then maintained at this value until the end of the reaction.

• · ·. * The workings described result in a silica slurry, “Il ·”. *, Which is then separated (liquid / solid separation). Separation • · · * · * * consists mainly of filtration, followed by washing if necessary. The filtration may, however, be carried out by any suitable method, for example a pressure filter or a belt filter or a circular filter, V. mella in a vacuum.

The thus obtained silica silica suspension (filter cake) 35 is then dried.

• · • · · · 13 ·

The drying may be carried out in any manner known per se.

Preferably, the drying is carried out by melting.

Any suitable nebulizer may be used, in particular a turbine, nozzle, fluid pressure or dual fluid atomizer.

10

In one embodiment of the manufacturing process, the suspension to be dried has a solids content of more than 18% by weight, preferably more than 20% by weight. Drying is then usually carried out with a turbine atomizer or, more preferably, a nozzle atomizer. 15

According to this embodiment of the invention, the precipitated silica, the silica precipitate, is usually in the form of substantially spherical spheres, preferably having an average size of at least 80 µπι. Such a solids content 20 can be achieved directly from the filtration using a suitable filter to provide a filter cake having a good content. Another way is to add me • · · · '** after filtering; The final step in the process is to dry the cake, for example ···. powdered silica so that the required • · ·. ·,; 25 concentration.

Note that, as is commonly known, the cake thus obtained is generally not in a form suitable for blending due to its excessive viscosity.

··· • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · This step can be accomplished by putting the cake in colloid or • · · • ·. ···. a ball type mill. In order to reduce the viscosity of the suspension to be melted, aluminum may be added, particularly in the form of sodium aluminate during the process, as described in FR-A-2536380, which is hereby incorporated by reference. This addition can be made especially during the decomposition.

After drying, it is possible to proceed to the comminution step of the recovered product, in particular the product obtained by drying a suspension having a solids content of more than 18% by weight. The resulting silica is usually in the form of a powder, preferably having an average particle size of at least 10 µm, especially 20-150 µm, for example 30-100 µm.

Products comminuted to the desired grain size can be distinguished from possible substandard products by, for example, vibration screens with suitable holes, and products of an incorrect size 15 can be returned to the comminution step.

Similarly, according to one embodiment of the invention, the dry matter content of the suspension to be dried is less than 18% by weight. In this case, drying is usually carried out with a turbine or nozzle mouthpiece. According to this embodiment of the invention, the resulting silica is usually in powder form, preferably with a particle size of at least 15 µm, in particular between 20 and 150 µm, for example between 30 and 100 µm.

**: 25 Here too, a decomposition operation can be performed.

Finally, the dried (especially from a suspension having a solids content of less than 18% by weight) or comminuted product may be aggressed according to an embodiment of the invention. 30 letting go.

By "agglomeration" we mean here all methods by which two finely divided objects are joined, so that; that they become larger in size and more mechanically durable. : 35 properties.

Such methods include, in particular, direct compression, wet granulation (i.e., use of a binder such as water or silica slurry), extrusion and, preferably, dry compaction.

Using this latter technique, it may be advantageous to perform de-aeration (a process also known as pre-density or degassing) on powdered products prior to compaction to remove the air they contain and to ensure a smoother compaction.

According to this embodiment of the invention, the resulting silica is preferably in the form of granules, preferably at least 1 mm, in particular 1 to 10 mm, in grain size 15.

After the agglomeration step, the resulting products can be calibrated to the desired size, for example by screening, and then processed for future use.

20

The advantages of the precipitated silica obtained according to the process according to the invention are thus, inter alia, that they provide a simple, efficient and economical granule mass of the type mentioned above, especially with very common forming methods such as granulation or compacting without the excellent mutual reinforcing properties of these powders: · degraded, masked or even lost as previously possible with conventional powders.

• · · • · · · · ·. ···. The silicas according to the invention or the silicas produced according to the process according to the invention are particularly suitable for elastomers, both natural and synthetic, and especially for elastomers used in pneumatic tires. · '· For chopping. They provide excellent ♦ · · ···: 35 trade-offs between the various mechanical properties of elastomers, ♦ · · · · 16, in particular significantly improved elongation, fracture and tear strength as well as rheological properties.

The following examples illustrate the invention without, however, limiting it.

Example 1

A stainless steel reactor with a propeller stirrer and double jacketed heating is charged with 662 liters of 10 sodium silicate solutions (molar ratio SiO2 / Na2O 3.4) with a silica content of 10 g / l.

The starting silicate content, expressed as SiO 2, is thus 10 g / l in the base of the vessel. The solution is then heated to 85 ° C with stirring. The entire reaction is carried out at 85 ° C. Next, 80 g / l sulfuric acid solution is added over 3 minutes and 20 seconds at a flow rate of 10.2 l / min. After the addition, the degree of neutralization of the base of the vessel is 85%, i.e., 85% of the amount of Na 2 O present in the base is neutralized.

Then the reaction is added to the mixture simultaneously for 70 minutes • · * '! 1: 25 sulfuric acid solution, 80 g / l, at a flow rate of 10.2: 1 / min, and: · - Sodium silicate solution, expressed as silica at 13 0 g / l at a flow rate of 14,2 rpm.

30 • · • · · .1. During this simultaneous addition, the immediate neutralization rate is 92%, i.e., 92% of the added Na 2 O (min · · * ··· 1 nut) is neutralized.

After this simultaneous addition, the consolidation value is 19.6.

• · 17

Once all the silicate has been added, the sulfuric acid solution is further added at the same flow rate for 10 minutes. This additional amount adjusts the pH of the reaction mixture to 4.5.

5

A precipitated silica broth is obtained which is filtered and washed by means of a rotary filter under vacuum to finally give a silica cake having a heat loss of 87% (i.e. a dry matter content of 13% by weight.) 10 This cake is then simply liquefied mechanically. After this disintegration step, the resulting broth is sprayed with a turbine atomizer.

The resulting powdered silica P1 (according to the invention) has the following characteristics: -CTAB specific surface area 125 m2 / g -BET specific surface area 164 m2 / g 20 pore volume V1. (pores <40nm) 0.58 cm3 / g · · · · · · · pore volume V2 · · · · · · · · · · · · · · · · 1 1 1 1 1 (1 1 (1 1 ((1 pores 17.5nm <d <27.5nm) 0.14 cm3 / g: -i: ratio V1 / V2 24% • · · .1 ·: 25 average particle size 60 µm

Mt ·: :: The silica particles P1 are then subjected to a deagglomeration assay as previously described.

• · · • · · · · ·. ···. After ultrasonic de-agglomeration, they have a mean lobe size (? 50) of 2.35 µm and an ultrasonic de-agglomeration factor (FD) of V: 5.2 ml.

• · · · · 35 · 35

• · · -J

• ·· • · 18

Example 2

The procedure is the same as in Example 1 except for the simultaneous addition of sulfuric acid and sodium silicate. In other words:

A stainless steel reactor with a propeller stirrer and double jacket heating is charged with 662 liters of sodium silicate solution (molar ratio SiO 2 / Na 2 O 3.4) at a concentration of 10 g / l silica.

10

The starting silicate content, expressed as SiO 2, is thus 10 g / l in the base of the vessel. The solution is then heated to 85 ° C with stirring. The entire reaction is carried out at 85 ° C. Next, 80 g / l sulfuric acid solution is added over a period of 3 minutes and 20 seconds at a flow rate of 10.2 l / min. After the addition, the degree of neutralization of the base of the vessel is 85%, i.e., 85% of the amount of Na 2 O present in the base is neutralized.

The reaction mixture is then added simultaneously for 70 minutes. Sulfuric acid solution, 80 g / l, at a flow rate of 10.2 l / min, and 1 l / min, and ·. 1: 25 • · i - sodium silicate solution, expressed as silica • · · V! 230 g / l at a flow rate of 7.9 l / min.

; 1 · 1; During this simultaneous addition, the immediate neutralization .1 · 1. The amount is 30%, i.e. 93% of the added Na 2 O (per minute) is neutralized.

1 · After this simultaneous addition, the consolidation value is 19.2.

• · · • · · ··· ♦ • 19 ·

Once all the silicate has been added, the sulfuric acid solution is further added at the same flow rate for 10 minutes. This additional amount adjusts the pH of the reaction mixture to 4.5.

A precipitated silica broth is obtained which is filtered and washed by means of a rotary filter under vacuum to finally give a silica cake with a heat loss of 87.1% (i.e., a dry matter content of 12.9% by weight).

This cake is then simply liquefied mechanically. After this disintegration step, the resulting broth is sprayed with a turbine atomizer.

The specific characteristics of the resulting powdered silica P2 (according to the invention) are as follows: -CTAB specific surface area 100 m 2 / g BET specific surface area 138 m 2 / g pore volume Vl 20 (pores <40nm) 0.26 cm 3 / g . pore volume V2 • · “I (pores 17.5nm <d <27.5nm) 0.07 cm3 / g ·” 'ratio V1 / V2 27%' · · .5.1 average size 60 μπι • · 1 · · _. The silica particles P2 are then subjected to a deagglomeration test as previously described.

After ultrasonic agglomeration, their average shark, ···. The 30 echoes (0 50) are 3.6 μπι and the ultrasonic agglomeration factor (F) • · is 3.5 ml.

• · • i · • · · · · ·

Example 3. . ·. To a stainless steel reactor with • · · • · ·. : 35 propeller mixer and double jacket heating, apply 662 liters of · · · · · 20 sodium silicate solutions (molar ratio SiO2 / Na20 3.4) with a silica content of 10 g / l.

The starting silicate content, expressed as SiO 2, is thus 10 g / l in the base of vessel 5. The solution is then heated to 85 ° C with stirring. The entire reaction is carried out at 85 ° C. Next, a 80 g / l sulfuric acid solution is added over a period of 1 minute and 40 seconds at a flow rate of 10.2 L / min. After the addition, the degree of neutralization of the base of the vessel is 85%, i.e., 85% of the amount of Na 2 O present in the base is neutralized.

Then, the reaction mixture is added simultaneously over 70 minutes: 15 - sulfuric acid solution, 80 g / l, at a flow rate of 10.2 l / min, and - sodium silicate solution, concentration: 20 130 g / l, at a flow rate of 14.2 l / min.

• · · During this simultaneous addition, the instant neutralization amount is 92%, i.e., 92% of the added Na, 0 (mi- * .i. * Per noodle) is neutralized.

V * l 25: After this simultaneous addition, the consolidation value is 39.0.

··· · M »

• I I

• I · •

After all the silicate has been added, continue to add sulfuric acids. adding po solution at the same flow rate for 10 minutes • · · 30. This additional amount adjusts the pH of the reaction mixture to 4.5.

A precipitated silica broth is obtained, which is filtered and washed with a circular filter in a vacuum to finally obtain. '·. a silica cake with a heat loss of 87% (i.e. «· · t ·] '; 35 dry matter content 13% by weight.) • This cake is then simply liquefied mechanically. After this decomposition step, the resulting broth is sprayed with a turbine atomizer.

The powdered silica P3 (according to the invention) obtained has the following characteristics: -CTAB specific surface area 119 m 2 / g -BET specific surface area 137 m 2 / g

pore volume VI

10 (pores <40nm) 0.38 cm3 / g pore volume V2 (pores 17.5nm <d <27.5nm) 0.10 cm3 / g ratio VI / V2 26% average size 60 μπι 15

The silica particles P3 are then subjected to a deagglomeration test as previously described.

After ultrasonic de-agglomeration, they have a mean diameter (0 50) of 2.3 μιη and an ultrasonic de-agglomeration factor (FD). is 5.0 ml.

• · · »· · ··· ··· • * ··· 1 Example 4 • · ·

A stainless steel reactor with • · 25 propeller stirrer and double jacket heating is charged with 662 liters of sodium silicate solution (molar ratio SiO 2 / Na 2 O 3.4) with a concentration of 10 g / l expressed as ϊ Γ.

The initial silicate content, expressed as SiO2, is thus · · · · · · · · · · · · · · · · · · · · · · ·........ 3 0 in basic 10 g / l. The solution is then heated to 85 ° C with stirring. The entire reaction is carried out at 85 ° C. Next, · · * .1 · · over a period of 3 minutes and 20 seconds, add 80 g / l sulfuric acid solution at a flow rate of 10.2 rpm. This one. . ·. after addition, the base portion of the vessel has a degree of neutralization of 85%, i.e., 85% of the amount of Na 2 O present in the base is neutralized.

Then, to the reaction mixture is added simultaneously for 70 minutes: - sulfuric acid solution, 80 g / l, at a flow rate of 9.9 l / min, and 10 - sodium silicate solution, concentration of 130 g / l, at a flow rate of 14.2 l / min.

The temperature of the reaction mixture is maintained at 85 ° C for the first 50 minutes of simultaneous addition, then raised to 85 ° C for 5 minutes and then maintained at 90 ° C until completion of the reaction.

During this simultaneous addition, the immediate neutralization rate is 90%, i.e. 90% of the added Na 2 O (mi-20 per noodle) is neutralized.

After this simultaneous increase, the consolidation value is 19.5.

***: After all the silicate has been added, continue with sulfuric acid; Addition of 25 po solutions at the same flow rate for 10 minutes • ··: This additional amount adjusts the pH of the reaction mixture to 4.5.

The reaction mixture is then allowed to mature for 10 minutes (with stirring, 90 ° C).

30. A precipitated silica broth is obtained which is filtered and washed with a circular filter in a vacuum to finally produce a silica cake with a 87% heating weight loss (i.e., · · · · · · · · · · · · · · · · · · · · · · · · · dry matter content 13% by weight.) 23 This cake is then simply liquefied mechanically. After this disintegration step, the resulting broth is sprayed with a turbine atomizer.

The resulting powdered silica P4 (according to the invention) has the following characteristics: -CTAB specific surface area 109 m2 / g -BET specific surface area 136 m2 / g

10 pore volume VI

(pores <40nm) 0.38 cm3 / g pore volume V2 (pores 17.5nm <d <27.5nm) 0.12 cm3 / g ratio VI / V2 32% 15 average size 60 μπι

The silica particles P4 are then subjected to a deagglomeration test as previously described.

After ultrasound agglomeration, they have a mean diameter (0 50) of 3.0 µm and an ultrasound agglomeration factor (FD) of 4.0 ml.

***: Example 5 • · · ^ ——————; · 1 · 25 Proceed as in Example 4 except for the reaction. : at the temperature of the thiol mixture. In other words: 11.1 In a stainless steel reactor equipped with a propeller stirrer and double jacket heating, 662 liters of 30% sodium silicate solution (molar ratio SiO2 / Na2O 3.4) are charged. ) with a content of 10 g / l expressed as 1 1 silica.

The initial silicate content, expressed as 1: 1: si02, is therefore in the container. 10 g / l in the base. The solution is then heated to 85 ° C while stirring. The entire reaction is carried out at 85 ° C. Next, 24 g sulfuric acid solution, 80 g / l, is added at a flow rate of 10.2 rpm over 3 minutes and 20 seconds. After the addition, the degree of neutralization of the base of the vessel is 85%, i.e. 85% of the amount of Na 2 O present in the base is neutralized.

Then, the reaction mixture is added simultaneously over a period of 70 minutes: 10 - sulfuric acid solution, 80 g / l, at a flow rate of 9.9 l / min, and - sodium silicate solution, 130 g / l, expressed as silica, at a flow rate of 14.2 l / min.

15

The temperature of the reaction mixture is maintained at 80 ° C for the first 50 minutes of simultaneous addition, then raised to 80-95 ° C for 7 minutes and then maintained at 95 ° C until completion of the reaction.

During this simultaneous addition, the immediate neutralization rate is 90%, i.e., 90% of the added Na 2 O (mi-: ϊ per noodle) is neutralized.

··· '• · · • • • · · · «. 25 After this simultaneous increase, the consolidation value is 19.5.

··· • · · · · • 1 · · 1, ·. When all the silicate has been added, continue to add sulfuric acid solution at the same flow rate for 10 minutes.

This additional amount adjusts the pH of the reaction mixture to 4.5.

30 ··· • · · * .1 'Then the reaction mixture is allowed to cook for 10 minutes ··· (with stirring, temperature 95 ° C).

«· • · · • · · ·. ···. A precipitated silica broth is obtained which is filtered and washed in vacuo to provide a final silica cake with a weight loss of 87% (i.e., a dry matter content). 13% by weight.) This cake is then simply liquefied mechanically. After this disintegration step, the resulting broth is sprayed with a turbine atomizer.

The resulting powdered silica P5 (according to the invention) has the following characteristics: 10 -CTAB specific surface area 118 m2 / g BET specific surface area 160 m2 / g pore volume V1 (pores <40nm) 0.48 cm3 / g 15 pore volume V2 (pores 17.5nm <d <27.5nm) 0.11 cm3 / g ratio VI / V2 average size of 23% particles 60 µm The silica particles P5 are then subjected to a deagglomeration test as previously described.

: After ultrasonic de-agglomeration, they have a mean lobe (0 50) of 2.6 µm and an ultrasonic de-agglomeration factor (FD) of · · ·. 25 ml is 4.2 ml.

· · · · · · · · · · · · ·

Example 6 · · · ...... ,, • · ·

A stainless steel reactor with • 1 · 1 · 1 propeller stirrer and double jacket heating is charged with 30 · · · V · - 626 liters of water and · · · - 36 liters of sodium silicate solution (molar ratio SiO2 / Na2O 3.6). at a concentration of 130 g / l.

••••••••••••••••••••••••••••••••••••••••••••••••••••••••

The starting silicate content, expressed as SiO 2, is thus 7.1 g / l in the base of the vessel. The solution is then heated to 95 ° C with stirring. The entire reaction is carried out at 95 ° C. Next, 80 g / l sulfuric acid solution (5) is added over a period of 3 minutes and 30 seconds at a flow rate of 5.4 l / min. After the addition, the degree of neutralization of the base of the vessel is 67%, i.e. 67% of the amount of Na 2 O present in the base is neutralized.

The sulfuric acid solution, 80 g / l, at a flow rate of 5.4 l / min, and 15, sodium silicate solution, concentration of 130 g / l, at a flow rate of 8.8 l / min are then added simultaneously to the reaction mixture.

During this simultaneous addition, the amount of immediate neutralization 20 is 83%, i.e., 83% of the added amount of Na 2 O (per minute) is neutralized.

: After this simultaneous addition, the consolidation value is 17.1.

• · · • • • • •. 25 After all the silicate has been added, continue to add sulfuric acid. : adding po solution at the same flow rate for 10 minutes • · · •. This additional amount adjusts the pH of the reaction mixture to 4.5.

The reaction mixture is then allowed to mature for 10 minutes 30 (with stirring, 95 ° C).

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Produce a broth of silica, which is filtered and washed with a pressure filter to finally produce a silicone cake with a heat loss of 78% - • · 35 dye content 22% by weight).

This cake is then liquefied mechanically and chemically (sodium aluminate addition, corresponding to Al / SiO2 3000 ppm by weight). After this disintegration step, a pumping cake of pH 6.7 is obtained, which is then sprayed with a nozzle atomizer.

The resulting powdered silica P6 (according to the invention) has the following characteristics: 10TAB specific surface area 131 m2 / g BET specific surface area 145 m2 / g pore volume V1 (pores <40nm) 0.984cm3 / g 15 pore volume V2 ( pores 17.5nm <d <27.5nm) 0.40 cm3 / g ratio V1 / V2 48% - average spherical size 200 µm The silica P6 is then subjected to a deagglomeration test as previously described.

After ultrasonic de-agglomeration, they have a mean diameter (0 50) of 3.7 µm and an ultrasonic de-agglomeration factor (FD) of «·. 25 is 11.0 ml.

Example 7 • · · * 11. "A stainless steel reactor with a propeller stirrer and double jacket heating is charged with 30 • · · * .1 1 - 853. liters of water, and · · · - 18.4 liters of sodium silicate solution (molar ratio SiO2 / Na2O 3.5) with a silica content of 237 g / l.

• · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

The starting silicate content, expressed as SiO 2, is thus 5 g / l in the base of the vessel. The solution is then heated to 85 ° C with stirring. The entire reaction is carried out at 85 ° C with stirring. Next, 5 sulfuric acids diluted at 20 ° C with a density of 1.050 at a flow rate of 4.8 L / min are added over a period of 3 minutes and 20 seconds. After this addition, the base of the vessel has a degree of neutralization of 91%, i.e., 91% of the amount of Na 2 O present in the base has been neutralized.

The sodium silicate solution as described above is then added simultaneously to the reaction mixture at a flow rate of 5.4 l / min and a sulfuric acid solution diluted in the same manner, at a constant flow rate, so that the pH of the reaction mixture is maintained at 15 ± 8.5 ± 0.15. and - at 7.8 ± 0.1 for the last 45 minutes.

During this simultaneous addition, the amount of immediate neutralization 20 is 92%, i.e., 92% of the added Na 2 O (per minute) is neutralized.

After this increase in age, the consolidation value is 17.5.

• · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · after this addition. : addition, but continue to add dilute sulfuric acid, then · · ·:, ·. that the pH of the reaction mixture is lowered to 7 · 4 · 7 · 7 · 4 in 7 minutes.

The addition of the acid is then stopped and the reaction mixture is stirred for a further 10 minutes at 85 ° C.

• · · • · • · · ·. · .1. A precipitate of silica is obtained which is filtered and washed. pressure filter to finally get a silica gel cake with a heat loss of 81% (ie a dry matter content of 19% by weight). .

This cake is then mechanically and chemically liquefied (sodium aluminate addition corresponding to a weight ratio of Al / SiO 2 at 2500 ppm and sulfuric acid addition). Following this disintegration step, a pumping cake having a pH of 6.5 is obtained and then sprayed with a nozzle atomizer.

The characteristics of silica P7 (according to the invention) in the form of substantially round spheres are as follows: -CTAB specific surface area 123 m2 / g -BET specific surface area 136 m2 / g

15 pore volume VI

(pores <40nm) 0.77 cm3 / g pore volume V2 (pores 17.5nm <d <27.5nm) 0.21 cm3 / g ratio VI / V2 27% 20 - average particle size 250 µm

The silica particles P7 are then subjected to a deagglomeration test as described previously in the description.

After ultrasound agglomeration, their mean shark (0 50) is 2.9 µm and the ultrasonic agglomeration factor (FD) is:. is 14.5 ml.

• »· ··· · ··· • ♦ ♦ • · ♦

Example 8 ... 30 By way of comparison, three silica having a specific surface area of 100-140 m / g of CTAB, which can be used as reinforcing fillers in elastomers, were studied. These were:. - on the other hand, two commercial powdered silica: ··· 35 • PERKASIL KS®300 (hereinafter referred to as PCI) powder sold by Societe AKZO, - · · · 35 · powder ULTRASIL VN2 (hereinafter referred to as PC2) sold by Societe DEGUSSA, 5 - on the other hand, XEOSIL® 125 MP (hereinafter referred to as MPI hereinafter) sold in the form of substantially spherical silica sold by RHONE-POULENC CHIMIE.

The characteristics of these silicas are summarized in Table 1 below. For purposes of comparison, the characteristics of the silicas P1 to P7 of the invention are also included in the table.

• · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·––––––––––––– »» »• · · · · · · ··········•••••••••••••••••••••••• • · · • ·· • · r- tH in oo vn r- cn ι> o - l> CN 00 - - CN LT) cn

p t — It — I O O CN t — I

^ O CO o tHinco ^ pooo -

KO oo ^ t <- - np o oo t — I

p t — I t — I O O. CN t — I

00 tH VO CN

CO O ^ tH 00 O - m tH vo - - cn vo oq ^ f

{¾ tH tH O O

00 CN O O

σ vo oo tH cn o - o oo - - oo vo oo

Pm t — it — I o o oo o o σ ο oo tH vo o oo oo tH oo - - cn vo -in

Pm tH tH O O CN

tH »nr 'm ococNor-o vo O cn o oo - - cn vo - oo US p tH tH o o oo US_________

D

J oo t-f m cn

Id in ^ intH ^ fo oo - • <| tH cn vo - - cn vo -in

• 1 · Eh Pm t — I t — I O O CN

··· tH _________ ··· oo

· _ _ · ^ O O CN

• tH in vo ^ tH oo m - -

. ·· p CN CN '- CN Γ "σ CN

·.:. 1 S tH tH O O CN

•. - -. II. .1.1— - - - - - - • «· * · 1ί ^ oo oo ·· CN CNCN ^ fOCOr- ::: o m ^ - - tH tH o -

···· p tH tH O O tH CN

··· • · · .............. '• · · • tH ό m tH VO VO LT) tH tH - tH00 U CN CN' - 00 tH - -

... ptHtHOO tH f «CN

• · ·! ·; ·: »S» »ί jl 5 _

* ^ \ ^ ci ___ · __I

• · cn oo on Ph - - · Η ::: ε "g ε ε h -h g. 3 υ υ> x o s ~

··· <tH 03 Q

:: u m tH CN CN 0 O P

* ·· CP m>>> us Λί Φ _________ • 1 • · · · · · · · 32

Example 9 This example illustrates the use and behavior of the inventive silica and prior art silica in industrial rubber formulation.

The formulation used was (in parts by weight): - S.B.R. 17121 rubber 100 - silica 51 10 - active ZnO2 1.81 - stearic acid 0.35 - 6PPD3 1.45 - CBS4 1.3 - DPG5 1.45 15 - sulfur6 1.1 - silane X50S7 8.13 1 styrene-butadiene copolymer of the type 1712 2 rubber grade zinc oxide 20 3 N- (dimethyl-1,3-butyl) -N'-phenyl-p-phenylenediamine 4 N-cyclohexyl-2-benzothiazylsulfenamide 5 diphenylguanidine. . ·. 6 vulcanizing agent • · ·. ···. 7 silica / rubber compound (product marketed by DEGUSSA) ***: '25h · Formulations are prepared in the following manner: • Inner mixer (type BANBURY) ) are placed in parenthesis • · · · in the order, time and temperature indicated: 30: T: - SBR 1712 (t0) (55 ° C): 3: - X50S and 2/3 silica (tn + 1 min) (90 ° C) - ZnO, stearic acid, 6PPD and 1/3 of silica (t +2 min) * · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 3 • · 33

The agitator is emptied (settled mixture) at a chamber temperature of 165 ° C (i.e., about t0 + 5min). The mixture is placed in a cylinder stirrer which is kept at 30 degrees C for calendering. To this mixer is added CBS, DPG and 5 sulfur.

After homogenization and three runs, the final mixture is calendered into 2.5 x 3mm thick sheets.

The results of the experiments were: 1 - Rheological properties

Measurements of the formulations were made in the raw state at 150 ° C. 15

The results are shown in Table 2 below. The equipment used in the measurements is mentioned.

TABLE 2 2 0 P1 P4 P5 P6 PCI PC 2 MPl. ... MOONEY consis- 22.6 21.1 22.6 18.9 28.9 23.2 31.2 • · · • · ·. 1 ... tensi • · • · —— III. I I I- • · ·: Minimum Moment2 70.9 69.7 70.5 69.8 82.7 79.7 86.7 • · · · · · ·

: 1 Rheometer MONSANTO 100 S

• · · • · · · ·

The formulations according to the invention achieved lower values of 1: 1: 25.

• · · • · • · · · · .1. This means that the alloys prepared from the silicas of the invention are easier to handle, especially in the extrusion and calendering work steps, which are often • · 34 is used in the manufacture of pneumatic tires (lower energy consumption for blending, better sprayability during mixing, less swelling in the nozzle during extrusion, reduced shrinkage in calendering 5, etc.) 2 - Mechanical properties

Measurements were made for the vulcanized formulations.

10

The vulcanization was performed by bringing the formulations to 150 ° C for 40 minutes.

The following standards were used: 15 i) Tensile strength test (modulus 100%, tensile strength, elongation at break) NFT 46-002 or ISO 37-1977 ii) Tear strength test 20 DIN 53-507 iii) Abrasion resistance test DIN 53-516 • · · · · ··· $ · * '1 25 The results obtained are shown in Table 3 below.

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 35 TABLE 3

Pl P4 P5 PC6 PCI PC2 PCl MPl

Module 2.2 2.4 2.4 1.8 3.3 2.7 3.8 100% (MPa)

Tensile strength 22.3 20.7 22.5 24.9 19.2 20.1 19.5 (MPa)

Elongation at break 490 470 500 593 397 419 375 (%)

Tear strength 20.0 16.3 27.2 27.4 11.5 14.3 9.7 (kN / m) 5 These recent results clearly demonstrate an improvement in the reinforcing properties of the silicas of the present invention relative to the prior art silica having a theoretical reinforcing capacity. however, it is the same.

10

The smaller »· · III modules present in the silica according to the invention are 100% proof of the good dispersibility of the silica.

The improved reinforcing capacity of the silicas according to the invention is expressed in higher values of tensile and tear strength and ··· V: elongation at break.

··· • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · exposure · · · · · · · · · · · · - - - - · · · · · ·

Claims (16)

1. Precipitated silica, characterized in that it has a - CTAB specific surface area (SCTAB) of 100-140 m2 / g, 5. a pore distribution such that its pore volume is comprised of pores having a diameter of 17.5-27.5 nm, represents less than 50% of the pore volume formed by pores having a diameter of 40 nm or less, - an average diameter (05O) of less than 4.5 (µm) after ultrasonic agglomeration and of at least one of the following forms: in the form of substantially circular spheres of at least 80 µm, in the form of a powder of an average size of at least 15 µm, and in the form of granules of a size of at least 1 mm. 2. Dioxide enligt patent krav 1, nipple tip av att den 10 uppvisar en ultraljuddesagglomerationsctor (FD) sachet 3 ml. Silicon dioxide according to claim 1, characterized in that it has an ultrasonic agglomeration factor (FD) of more than 20 ml. : 3. Silica according to claim 1 or 2, characterized by ··· ·· 1. having an average size of at least 80 (im ···......) in the form of substantially round spheres and having an average diameter of · · · V ′ · 25 after ultrasonic agglomeration • ·· .1 (05O) less than 3.1 ( lm and ultrasonic agglomeration blank (F) are greater than 8 ml. 3. Dioxide enligt face av patent 1 eter 2, kangetecknad av att den föreligger i form av sfäriska Kulor med 15 en genomsnittlig storlek av minst 80 μιη och att denis mediandiameter (05o) after desagglomeration med ultraljud 3,1 μιη ultraljuddesagglomerationsfak-Tor (FD) graft 8 ml. 4. Dioxide enligt face av patent craven 1-3, banners av att den har en specif BET (SBET) bag 100-210 m2 / g. • · · · · · · · · · · · · · · · · · · · · · · · · · , 0-1.2.: M 25 •: *: 6. Kieselguhr enligt face av patentkraven 1-4, kanknetecknad ··· · av att den uppvisar et förhällande (SBET) / (SOTAB) som överstiger 1,2. · ··· · · · · I .. 30 7. Kissing Dioxide enligt face av patentkraven 1-6, nipple tips • · · · · · · · · · · · · · · · · · · · · · • · Silica according to any one of claims 1 to 3, characterized in that it has a BET specific surface area (SBET) of 100-210 m2 / g. Silica according to any one of claims 1 to 4, characterized in that its ratio (SBET) / (SCTAB) is 1.0-1.2. • · · I- • · · 35 ··· · · · · · · · · Silica according to one of Claims 1 to 4, characterized in that it has a ratio (SBET) / (SCTAB) of more than 1.2. Silica according to any one of Claims 1 to 6, characterized in that it has an oil absorption value DOP of 150-400 ml / 100 g. 8. Förfarande för framställning av kitsioxid enligt face av ♦ · · l \ 35 patent kraven 1-7, av den typ som innefattar reaction av et · · · · ♦ ♦ · silicon av alkali metal Mmed ett surgöringsmedel, genomic flash man erhäller en suspension av utfälld emulsion dioxide, och däref ter such suspension separator och throat, telecommand av att utfällningen genomförs main: 5 (i) total number of alkali metal silicates, quantitatively available, Si02, this bottlesats uppgär högst account 11 g / 1, 10 ii) man tillsätter surgöringsmedlet account these bottlesats till dess att minst 50% av quantitat M20 som föreligger i these bottensats and neutralizes, 15 iii) man tillsätter account reacttionsblandochörningid samt. Quantity of alkali metal silicates Quantity of silicate quartz, uttry ckt som SiO2) / Quantitative silica in bottlenose (uttryckt si SiO2) ligand 12 and 100. 20 A process for the production of silica according to any one of claims 1 to 7, which is of a type which comprises reacting an alkali metal M silicate with an acidifying agent to obtain a slurry of silica and then separating and drying, i) forming a base portion of the vessel containing a portion of the total amount of silicate of the alkali metal M used for the reaction, expressed as SiO 2 in the base, up to 11 g / l, 20 ii) adding an acidifying agent to the base until at least 50% the amount of M20 present in the base is neutralized; add at the same time to the reaction mixture both acidifying substances and the remainder of the amount of alkali metal M silicate,. so that the ratio of the amount of silicate added (expressed as · · · · ··· * SiO 2) / the amount of silicate present (expressed as SiO 2) in the base is 12 to 100. The process according to claim 8, characterized in that in step iii), both the acidifying agent and the remainder of the alkali metal M are simultaneously added to the reaction mixture. * ··. the amount of silicate so that the ratio of the amount of added silica · · · • # / amount of silica present in the base is 12-50. • · · ··: · * 35 • · • · · · · · · · 9. FÖrfarande enligt patentkrav 8, kännetecknat av att i steg • · · · · · · · · · · · · · · · · · · · · att förhällandet mellan Quantity of tillsatt silicates och: \ i 25 silicates närvarande i bottensatsen ligger mellan 12 och 50. · · · · · · · · · · · · · · · · · · · · · · · · · · · 10. FÖrfarande enligt face av patentkraven 8 eller 9, kännetecknat av att efter steg iii) tillsmettning account reac- # ... tionsmiljön en tillsatsmängd surgöringsmedel, företrädesvis • · · 3. save att reactionmil pH pH blir 3-6,5. • · • · • · · Process according to claim 8 or 9, characterized in that after step iii) an additional acidifying agent is added to the reaction mixture, preferably so that the pH of the reaction mixture is 3-6.5. 5 11. FÖrfarande enligt face av patentkraven 8-10, kännetecknat ·; · *: av att playden surgöringsmedel som tillsätts under hela steg iii) shine, att 80-99% av den tillsatta play M, O • · · I *. 35 Neutralizer. • · · • · · · The process according to any one of claims 8 to 10, characterized in that the amount of acidifying agent to be added throughout step iii) is such that 80 to 99% of the added M20 is neutralized. 10 12. Förfarande enligt face av patentkraven 8-11, electrolyte användecknat av att ingen används. 13. Genomic atomization of Förfarande enligt face av patentkraven 8-12, kännetecknat av att torkningen utförs. Process according to one of Claims 8 to 11, characterized in that no electrolyte is used. Process according to one of Claims 8 to 12, characterized in that the drying is carried out by killing. 14. Förfarande enligt patentkrav 13, kännetecknat av att den torkade produkten därefter agglomereras. 10 Process according to claim 13, characterized in that the dried product is then agglomerated. 15. Förfarande enligt patentkrav 14, kännetecknat av att den torkade producten xnals, och därefter valbart agglomereras. Method according to claim 14, characterized. • grinding the dried product and then optionally agglomerating it. • · • · • · · Use of silica according to any one of claims 1 to 7 as a reinforcing filler for elastomers. · · ♦ ♦ ♦ ♦ «« «« «« «« «« l l 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. ld ld ld 1. ld ld ld 1. ld ld ld 1. ld ld ld 1. ld 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. eld 1. 1. 1. eld 1. 1. 1. f 30 * - en spec CTAB (S ^) at 100 and 140 m2 / g, • · # - I adjust porfördelning att porvolymen som utgöres av Porer, *: * "vars diameter 17.5-27.5 nm, utgör mindre än 50% av .V. porvolymen som bestär av Porer med en diameter om 40 nm eller • · · l *. 35 for all, • · · ♦ · · · - mediandiameter (05O) after desagglomeration med ultrasolid som understiger 4.5 μιη, och att den föreligger i minst en av feljande former: fatigue spherical Kulor med en genomsnittlig storlek av 5 minst 80 μπι, Pulver med en genomsnittlig storlek av minst 15 μιη, och granulat med en storlek av minst 1 mm. 16. Användning av avselidid dioxide enligt face av patentkraven 1-7 15 som Förstärkande Fyllmedel for elastomerer. •••••••••••••••••••••••••••••••••••••••••••••••••••••• · ♦ · · · «· · · t t t t t t t t t t t t t t t t t ·· • ·